The Qur’an uses the general and particular methods in refuting the Christian belief in Trinity.

In the general method, the Qur’an shows that it is impossible for God to take a son for Himself, no matter whether the presumed son be Jesus or someone else. In the particular method, the relevant verses describe that Jesus, son of Mary, was neither the son of God nor God but he was simply a servant created by God.

When we try to expound the meaning of sonship and birth as we are are all familiar with, we find that such a thing is impossible for God, for the following reasons:

• Because it needs a physical material body and God is far above this.
• To God belongs absolute Divinity and Lordship and therefore it is impossible to imagine a thing similar to God in species having the same identity and characteristics similar to those of God.
• If God could beget or give birth to a son, it would entail graduality of action for God. Rather, He would be governed by the laws of matter which is a contradiction because whatever takes place by His will, comes into being at once, without delay.

The above stated reasons are inferred from the following verses:

And they say: Allah has taken to himself a son. Glory be to Him; rather, whatever is in the heavens and the earth is His; all are obedient to Him. The Originator of the heavens and the earth; and when He decrees an affair, He only says to it, Be, and it is. (2:116-117)

The author of al-Mizan makes an interesting comment on the clause, The originator of the heavens and the earth as follows:

It is also possible to take the clause, The Originator of the heavens and the earth, as an allegorical expression in which the attribute of the object has been transferred to the subject. In other words, the clause may denote that the heavens and the earth are original in their creation and design; God has created them without any previous model. Therefore, He cannot beget anyone, otherwise it would be a creation on His own model. (After all, the Christians believe that the Son is one with the Father.) In that case this clause would be an independent proof by itself.

– Allamah Tabataba’i (English Vol. 6)

In the second method employed by the Qur’an, it asserts that Jesus, son of Mary could not be a son of God sharing Godhead with Him, because he was a human being having all the concomitants of humanity. His (that is, Jesus) condition, from the time he was conceived by Mary until he reached the matured age was like any other normal human being in the progression of life. This method is inferred in the following verses:

Certainly they disbelieve who say: Surely Allah is the third (Person) of the three ; and there is no god but the One God, … The Messiah, son of Mary is but an apostle; apostles before him have indeed passed away; and his mother was a truthful woman, they both used to eat food. See how We make the signs clear to them, then behold how they are turned away (5:73-75).

The author makes a striking comment on the clause, they both used to eat food as follows:

Eating food has been specially selected for mention in preference to other activities, because it rather more forcefully proves his materiality and shows his neediness and wants, which cannot be combined with Godhead. Obviously, a person who by his nature feels hunger and thirst and satisfies it with a morsel of food and a cup of water, is nothing but an embodiment of poverty and need—a need that cannot be removed without help of some extraneous agent. How can such a man be God? What is the meaning of such divinity?

– Allamah Tabataba’i (English Vol. 6)